some critical points are:
- just like with money, with piano technique there is something like inflation:
1$ in 1900 is not 1 $ now
a fast octave in 1845 is not the same as a fast octave now. You might argue: it is the same eg 10/sec then is 10/sec now but it is not the same when we compare this speed to what is the "average octave speed of all the piano playing population of that time compared to now":
It is clear that an average pianist of today plays octaves better (technically whatever that means) then in the time of Liszt (keeping all other parameters constant eg weight action/type of piano etc). Proof: eg Tschaikowksky piano concerto octaves were considered as extremely difficult to unplayable at the time. Now many recordings exist (i know that there are more human beings on the planet now too).
- this brings up an important point: it is not only about "is someone from 1845 better then someone from today?" because there are too many changing factors such as the piano evolution itself, the number of people that have access to a piano, the total human population, the availability of knowledge (very important as everyone who has ever used a tip from the forum here will know), the structure of this knowledge, the composition methods/habits, ....
an important question is:
"Is Liszt relative to his contemporaries much better then today's top relative to her/his contemporaries?"

This is a better question. However two things are important here:
- it is so that the lower mankind is on a learning curve of some ability/technology, the easier it is to have a relative high advantage in relation to the mean of the population,
- the less people play the piano, the more chance there is one person can be much better then his contemporaries.
It is clear that in this respect Liszt had an advantage: much of piano technique was undiscovered when Liszt was young. Fewer people played piano.
So we can conclude that:
- if you have stellar technique today (à la Volodos/Sokolov), you will blow liszt away if transported back into time.
- of course this is not a fair comparison considering all what i've said above (eg access to knowledge)
- If Liszt were born today he will have stellar new millenium technique too.

All this said my vote for comparative best technique in relation to his contemporaries goes to ....... Liszt.
Remark: he arrived at the right time (on the learning curve) and that's also part of what made him great.
And when you say today's pianists are better you must think twice about one thing:
After Liszt the piano was not the same. He changed the rules forever.
